An agitator for mixing or blending various products, in particular paints, varnishes or the like

Abstract: An agitator for mixing or blending various products, in particular paints, varnishes or the like, disposed in a container (C), has a fixed support structure (20) which is resiliently connected to a first framework (11) which in turn supports a second framework (5) in a generally oscillatory manner. An upper plate (6) and a lower plate (2), rotatable about a vertical axis and mounted on the second framework, hold the container (C). When the machine is in use, an electric motor (14), mounted on the first framework (11), rotates a shaft (16) provided with pins (18) which are eccentric relative to the axis of rotation of the shaft (16) and are connected to the second framework (5). The actuation of the motor (14) gives rise to an orbital oscillatory motion of both frameworks (5, 11) together and the intermittent and unidirectional rotation of the lower plate (2) about a substantially vertical axis.

Description: The present invention relates to an agitator for mixing or blending various products. In particular, the present invention has been developed with respect to agitators for mixing or blending paints, varnishes or the like, generally placed in containers preferably having a substantially cylindrical shape, of the type comprising: a general support structure; a first framework resiliently connected to the support structure; a second framework which is associated with the first framework with a general capacity for relative oscillation; holding means associated with the second framework for clamping therebetween at least one of the containers containing the products to be mixed; operating means which are further provided for driving an orbital - oscillatory movement of the second framework relative to a reference axis which is fixed relative to the first framework (see e.g. GB-A-2 192 138, DE-A-2 819 833). In the current practice for producing a range of paints having, for example, a series of different colour shades, a base paint, generally a white paint, is usually mixed with one or more coloured pigments which are added in proportions such that the desired colour shade is ensured overall when they have been mixed and homogenized with the base paint. When paints are prepared according to the above mixing methods, it is increasingly necessary to produce different quantities from time to time depending on the demands and immediate needs of the users. In particular, a range of preferred amounts although not limiting, in the preparation of the paints and their mixtures can vary from small fractions of a litre to approximately 30 - 40 litres. The conventional mixing methods provide for different types of methods and agitators depending on the overall quantity of components to be mixed and their physical and chemical properties. For large amounts of relatively fluid paints, a machine of the type comprising a mechanical stirrer which is immersed in the paint is generally used and, for example, blends the components with a rotary motion. These machines are generally used only in large plants producing large amounts of paints since they do not allow the colour shade to be changed quickly without the entire stirrer being replaced, an operation which is generally complicated and expensive, especially for small amounts of paint in a broad spectrum of colours. For viscous, heavy and dense products and for medium-large amounts, apparatus with a gyroscopic effect are used in which the container for the paint to be blended is rotated about at least one axis. These machines are quite bulky and heavy and have long mixing times because the forces of inertia derived from the gyroscopic movement and from the masses involved increase when the amount of paint blended increases. For small or very small amounts, mixing is usually carried out manually which, in addition to involving long operating times, does not guarantee a satisfactory result in terms of homogeneity of the paint. The object of the present invention is to overcome the disadvantages of the prior art and in particular to provide an agitator which is simple and cheap to produce, which can also be used by unskilled users, and which permits quick and homogeneous mixing in a broad range of different amounts of products. A further object of the present invention is to produce a stable machine which does not transmit undesired vibrations to the environment and to the surrounding area, and which restricts the energy consumption required for its operation to a minimum. These objects are achieved by an agitator of the type mentioned above, characterised in that the holding means comprise a drive unit acting on the holding means to impart to the container a general rotational movement about a second axis, different from the reference axis and non-parallel thereto, which is superimposed on the orbital - oscillatory movement. Further characteristics and advantages will become clear from the following description, with reference to the appended drawings, given by way of non-limiting example, in which: Figure 1 is a schematic view in perspective of an agitator according to the present invention; Figure 2 is a schematic front view along the arrow II of Figure 1; and Figure 3 is a perspective view of a detail of the agitator of Figure 1. With reference to Figure 1, an agitator for mixing or blending various products, in particular paints, varnishes or the like, in a container C, shown in chain outline in Figure 1, is generally indicated 1. The container C rests on a lower plate element 2 rotatably mounted on a base 4 which is an integral part of a framework 5. The container C is closed at the top by an upper plate 6 rotatably mounted on a structure having appendages 7 with threaded bushes at their ends which engage worm screws 8 extending vertically and rotating relative to the platform 4. An electric motor 9 is mounted on the framework 5 and rotates the upper ends of the worm screws 8 by means of a toothed belt 10 and a pulley transmission, such that the upper plate 6 can be raised or lowered. As an alternative to the single toothed belt 10 which is illustrated, two toothed belts may be provided being wound respectively around one pulley mounted on the output shaft of the electric motor 9 and one pulley mounted on one of the worm screws 8, so as to equally balance the torque of the electric motor 9 applied to both the worm screws 8. The framework 5 is connected in an oscillatory manner to an outer framework 11 by connecting rods 12 which allow the upper portion of the framework 11 to oscillate relative to the upper portion of the framework 5. The outer framework 11 comprises a platform 13 on which an electric motor 14 is mounted which, by means of a toothed belt 15 and a pulley system, rotates a shaft 16 mounted for rotation about an axis X - X which is fixed relative to the framework 11. Two discs 17, which bear two pins 18 which are eccentric relative to the axis X - X of the shaft 16, are keyed to the ends of the shaft 16. The pins 18 are rotatably connected to the base 4 of the framework 5. A counterweight 33 is fixed on the shaft 16. The framework 11 is suspended by means of a system of springs 19 from a support structure 20 provided with support feet 21 which may be vertically adjustable. The framework 11 also has anti-oscillation brakes 32, for example of the friction type, coupled to the support structure 20. A system of suspension springs 22 associated with respective bars 23 and held in compression by stops 24 mounted on the bars 23 is interposed between the framework 5 and the outer framework 11. The function of these springs 22 is to discharge some of the weight of the container C from the framework 5 to the framework 11. The lower plate 2 is circular and has a toothed rim 25, preferably with straight or helical teeth, on its cylindrical peripheral surface. This toothed rim 25 is coupled to a pinion 26 rotated by means of a pin 27, by a ratchet unit 28 which is in turn coupled to a driving lever 29, of which the end opposite the ratchet unit 28 is articulated to the support structure 20 by a telescopic joint 30. The two ends of the joint 30 have ball joints 31 connected to the driving lever 29 and to the support structure 20 respectively. When the agitator according to the present invention is in operation, the container C containing the various products to be blended is loaded onto the lower plate 2. The electric motor 9 is actuated to rotate the worm screws 8 by means of the belt 10, causing the upper plate 6 to descend, which clamps the container C onto the lower plate 2. The electric motor 14 is then activated and, by means of the belt 15, rotates the shaft 16 about the axis X - X, this causing the framework 5 to rotate eccentrically with an orbital - oscillatory motion about the axis X - X by means of the pins 18. The overall oscillation of the two frameworks 5, 11 is at least partially counterbalanced by their own weight and by the counterweight 33. This oscillation relative to the fixed support structure 20 gives rise to an alternating relative oscillation of the driving bar 29 with respect to the support structure 20. This oscillation drives into rotation the ratchet device 28 which imparts a unidirectional and intermittent rotary motion to the lower plate 25 by means of the toothed wheel 26. After the electric motor 14 has been activated for a given amount of time, during which the agitator mixes the products in the container C, this motor is deactivated and the oscillatory motion of the frameworks 5 and 11 is braked by the anti-oscillation brakes 32. Subsequently, a rotation is imparted to the worm screws 8 by the actuation of the electric motor 9, in order to raise the upper plate 6 and thus release the container C containing the various blended products. An alternative to the adoption of the ratchet device 28 for imparting the rotary motion to the lower plate 2 consists of providing the agitator with an auxiliary electric motor which is electronically controlled and whose output shaft is operatively connected to the pinion 26. The electronic control of the auxiliary electric motor drives into rotation the pinion 26 according to a selectively predetermined law which may be for example a unidirectional and intermittent rotary motion, as the one accomplished by the ratchet device 28 described above, or, more generally a unidirectional or bidirectional rotary motion, either intermittent or continuous. Moreover, a further alternative embodiment of the invention disclosed in the present specification provides for an idle lower plate and an upper plate which is driven into rotation by a drive unit, either in the form of the ratchet device 28 or of the auxiliary electric motor hereinabove mentioned. This embodiment allows the lower plate to be slidably mounted on guide rails or similar supporting elements so as to be extracted at least partially from the support structure of the agitator for simplifying the operation of loading and unloading thereof.

Claims: An agitator for mixing or blending various products, in particular paints, or varnishes, placed in containers (C), comprising: a general support structure (20); a first framework (11) resiliently connected to the support structure (20); a second framework (5) which is associated with the first framework (11) with a capacity for relative oscillation; holding means (2, 6) associated with the second framework (5) for clamping therebetween at least one of the containers (C) containing the products to be mixed; operating means (14, 15, 16, 17, 18) which are further provided for driving an orbital - oscillatory movement of the second framework (5) relative to a reference axis (X - X) which is fixed relative to the first framework (11), characterized in that the holding means (2, 6) comprise a drive unit (25, 26, 27, 28, 29, 30) acting on the holding means to impart to the container (C) a general rotational movement about a second axis, different from and non-parallel to the reference axis (X - X) which is superimposed on the orbital - oscillatory movement. An agitator according to Claim 1, characterized in that the holding means (2, 6) comprise a first plate element (2) rotatably mounted on the first framework (5), comprising toothed transmission means (25) coupled to a pinion element (27) which is driven into rotation for imparting to the first plate element (2) said rotational movement about said second axis. An agitator according to Claim 2, characterized in that said first plate element (2) comprises at least one substantially cylindrical peripheral portion which is associated with a toothed rim (25) coupled to said pinion element (27), a ratchet unit (28) which can be activated by means of a driving bar (29) articulated to the support structure (20) driving the pinion (27) and hence the first plate element (2) in intermittent and unidirectional rotation. An agitator according to Claim 2, characterized in that said pinion element (27) is coupled to an auxiliary electric motor which is controlled to drive the pinion element (27) and hence the first plate element (2) into rotation. An agitator according to Claim 2, characterized in that said holding means comprise a second idle plate element (6) rotatably mounted on the first framework (5), said first and second plate elements (2, 6) cooperating, in use, for clamping at least one container (C). An agitator according to Claim 5, characterized in that second idle plate element (6) is disposed above the first plate element (2), guide means being provided for extracting at least partially the second plate element from the support structure for loading and unloading operation. An agitator according to Claim 1, characterized in that the holding means (2, 6) comprise at least one first holding element (2) which can move selectively in the direction of a second holding element (6). An agitator according to Claim 7, characterized in that the first holding element (2) comprises one or more appendages (7) associated with respective worm screws (8), the selective rotation of which determines the movement in one sense or the other, respectively, of the first holding element (2) in the direction of the second holding element (6). An agitator according to Claim 1, characterized in that it comprises at least one motor (14) associated with a shaft (16) rotatably supported by the second framework (11), the first framework (5) being coupled eccentrically to the shaft (16), the rotation of which, in operation, determines the orbital - oscillatory movement of the first framework (5).

Inventors: ROSSETTI EDOARDO, ROSSETTI, EDOARDO
Applicants: COROB SPA, COROB S.P.A.
Application year: 1994
Main classification: B01F11
IPC codes: B01F11, C09D7, B01F15